Muddy Waters: Three Hardy Natives in a Dynamic Riverscape

The flannelmouth sucker, bluehead sucker and roundtail chub, commonly referred to as “The Native 3,” have inhabited our waterways for 10 million years.
flannelmouth sucker, roundtailed chub, bluehead sucker
(Images left to right) Colorado Parks and Wildlife aquatics technicians: Jacob Eggers with a flannelmouth sucker captured on the Colorado River near Parachute; Jenn Logan with a large female roundtail chub captured in the Yampa River near Craig; John Cleveland holding a Bluehead Sucker on the White River near Rangely.

Co-authored by Dan Cammack and Jenn Logan

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Welcome to the American West, a land of extreme environments. When you think of Colorado, you may picture a clear mountain stream brimming with trout, with towering, snow-capped peaks in the backdrop. But as those silver ribbons tumble west of the Great Divide, they coalesce and gradually morph into something quite different – something warmer, murkier and more unpredictable. John Denver’s “Rocky Mountain High” is replaced by Edward Abbey’s scattered junipers and lonely sandstone vistas. 

As mountain waters flow west, scorching sun, torrential floods and severe droughts become common and conditions can change in the blink of an eye. The harshness of this landscape challenged westward expansion and caused many to write it off as a barren wasteland unfit for life, but three species of native fish may take issue with this assertion. 

The Native 3

electrofishing the Dolores River
CPW biologists electrofishing the Dolores River during extremely low flows below McPhee Reservoir in 2021. Photo © Jason Houston/Courtesy of The Nature Conservancy.

The flannelmouth sucker, bluehead sucker and roundtail chub, commonly referred to as “The Native 3,” have inhabited these waterways for 10 million years. They have learned to “roll with the punches.” With streamlined bodies, large fins and tough scales, they are equipped to withstand torrents of sand-infused water. When conditions are suboptimal, these desert track stars commonly roam between connected waterways, on their quest to feed, grow and reproduce. One might think such a hardcore lifestyle would not lend itself to longevity, but these natives commonly survive for decades.

It would be nice to say that wildlife agencies have always championed these fishes, respected them as an integral part of the ecosystem, and worked to understand and conserve them, but that isn’t the case. Aldo Leopold’s 1949 “land ethic” was not immediately embraced. Society largely wrote these species off as “trash fish” and sometimes went as far as to intentionally poison miles of sensitive habitat to make room for the “superior” non-native sportfish. 

The terms “sucker” and “chub” took on a negative connotation – a damaging legacy that is hard to shake even today. Their ventral, or abdominal facing mouths and bottom-feeding tendencies gave them a reputation as a “dirty” fish. Further, in humanity’s quest to convert a harsh landscape into something we could all inhabit, wild rivers were dammed, diverted, and tamed, leaving vulnerable habitats simplified, dissected and sometimes dry as a bone.

Alarming Declines

surveying the lower Dolores River
Southwest native aquatics and three species research teams combine forces to survey the lower Dolores River near Gateway, CO. Photo © Olivia Reinhardt (Western Colorado University).

Eventually, biologists realized that these resilient fishes were facing death by 1,000 cuts, and swift action was required to keep them on the face of the planet. Today, the three species occupy less than 50% of their former habitat and continue to face a litany of challenges. While this is alarming, it is not too late. Strongholds for these populations remain, and biologists are beginning to unravel the intricate strategies these species have adapted to survive and work to develop antidotes for the threats they face.  

Fisheries managers have adopted the use of passive integrated transponder (PIT) tags, more commonly known to pet owners as “microchips.” Combined with the strategic placement of antennas, this technology highlights when and where these fish move, helping to identify important habitats and migration corridors, while creating opportunities to reconnect waterways through the removal of man-made barriers or the creation of fish passage structures. Most inspiring, PIT tags have provided insights into the journeys these creatures embark on. 

Dry Streams Matter

Staff injects a roundtail chub with a passive integrated transponder (PIT) tag
A Colorado Parks and Wildlife biologist carefully injects a roundtail chub with a passive integrated transponder (PIT) tag for movement research. Photo © Jason Houston/Courtesy of The Nature Conservancy.

A stalwart flannelmouth sucker was tagged in the Green River in 2011 and was shown to have wandered at least 500 miles between Utah and Colorado since it was tagged, navigating canyons, turbulent waters, sandbar mazes and diversion structures, all while avoiding predators, coping with droughts, floods and competition by non-native species. PIT tags, along with fishery surveys, have unearthed a shocking revelation: dry streams matter. 

Small tributaries that are completely dry for most of the year provide fleeting, but critical habitats for these savvy natives. As snowmelt revives these parched channels, throngs of the three species ascend from larger rivers, converging to spawn en masse, then quickly vanish downstream leaving behind millions of eggs. What once was a dusty stream bed becomes a productive nursery harboring a new generation of native fish, drifting downstream with receding flows – an ancient dance of the West.

Rest assured that Colorado is snowcapped peaks and clear streams, but there are other beautiful and important features as well. Head downstream and embrace the stark desert landscape. Consider the vitality that emanates from the arteries of those haunting lands. You may not be able to see it, but just beneath that murky lens there is raw, willful survival on display. 

Coloradans pride themselves on resilience, adaptability, and frankly, living a lifestyle that seems a bit askew to outsiders. Native fish epitomize these values, but their future is uncertain, especially in a drying climate. It will take more than dedicated biologists to ensure that the three species persist. Committed stewardship by society at large can give these species a shot at survival, and if we have learned anything, “a shot” is about all they need.  

Perhaps retired Colorado Parks and Wildlife Aquatics Researcher Kevin Thompson said it best, “I know that most people recoil at the sight of a fish with a ventral mouth, but we ought to learn to do better.”  

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Learn more about “The Native 3” in a short documentary film that captures the work of researcher Zachary Hooley-Underwood as he works in critical spawning streams for roundtail chub, flannelmouth sucker and bluehead sucker with the goal of preventing further hybridization with non-native species such as the white sucker.


Co-authored by Dan Cammack and Jenn Logan. Dan is the Southwest Region Aquatic Conservation Biologist and Jenn is a Northwest Region Aquatic Conservation Biologist for Colorado Parks and Wildlife.

2 Responses

  1. I am not a fisherman & don’t remember where I learned about this newsletter being sent out but I truly appreciate it & read it. Recently we visited the Fish Hatchery at Leadville & will stop at others when out & about Colo. Thank You.

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